Compositions for surface cleaning in aerosol applications

ABSTRACT

When certain weight ratios of certain flammable additive components (an ether and an epoxyalkane) are blended in n-propyl bromide, the components can actually function as flame retardants or flame suppressants when the resulting cleaning composition is used in aerosol applications. The proportions of the additives used are small; yet suitably effective stabilization against metallic corrosion is achieved even at mildly elevated temperatures.

REFERENCE TO RELATED APPLICATIONS

This is a continuation of commonly owned copending Continued ProsecutionApplication (CPA) No. 09/151,822 U.S. Pat No. 6,258,770, which continuesthe prosecution of prior commonly-owned copending application Ser. No.09/151,822, filed Sept. 11, 1998.

TECHNICAL FIELD

This invention relates to novel, high performance solvent compositionswhich can be used safely in aerosol applications for cleaning surfaces,such as metal surfaces.

BACKGROUND

Recently, n-propyl bromide has been shown to be an excellent substitutefor chlorinated hydrocarbons as a cleaning and degreasing solvent.

U.S. Pat. No. 5,707,954 describes stabilized degreasing and cleaningsolvent compositions which are comprised of at least 90 wt % of n-propylbromide and a 1,4-dioxane-free stabilizer system which comprises2,2-dialkoxypropane. The stabilizer system may contain in addition anitroalkane, nitrobenzene, an epoxide such as 1,2-epoxybutane, and/or anamine. Efficacious results are shown in the example wherein a solventcomposition was composed of the following ingredients: 96.5 wt % ofn-propyl bromide, 2.5 wt % of 2,2-dimethoxypropane, 0.5 wt % of1,2-epoxybutane, and 0.5 wt % of nitromethane. The patent alsodescribes, inter alia, tests involving replacement of the 2.5 wt % of2,2-dimethoxypropane by 2.5 wt % of 1,3-dioxolane or 2.5 wt % of1,4-dioxane.

THE INVENTION

In one of its aspects, this invention involves the surprising discoverythat when certain weight ratios of certain flammable additive componentsare blended in n-propyl bromide, the components can actually function asflame retardants or flame suppressants when the resulting composition isused in aerosol applications. Thus, even though the composition is in ahighly dispersed or aerosol state—a condition which normally engendersincreased flammability—the composition is more flame resistant than ifthe particular flammable additive ingredients had not been blended inthe n-propyl bromide.

Another aspect of this invention is the discovery that certain verysmall amounts of flammable additives when blended in n-propyl bromideprovide suitably effective stabilization against metallic corrosion evenat mildly elevated temperatures. Indeed, this advantageous result can beachieved by use of very small concentrations of but two additives in then-propyl bromide.

Accordingly, this invention provides, in one of its embodiments, acomposition which comprises (I) n-propyl bromide having dissolvedtherein (ii) an ether, preferably a cyclic diether having a 5- or6-membered ring, and most preferably 1,3-dioxolane, and (iii) anepoxyalkane having in the range of 3 to about 7 carbon atoms in themolecule, preferably 1,2-epoxybutane, in proportions such that saidcomposition is nonflammable under the conditions of ASTM test procedureD 3065 using 1-fluoro-2,2,2-trifluoroethane as the propellant.

Another embodiment of this invention is a method of reducing theflammability of n-propyl bromide in aerosol applications (when testedunder the conditions of ASTM test procedure D 3065 using1-fluoro-2,2,2-trifluoroethane as the propellant), which methodcomprises blending with the n-propyl bromide (i) in the range of about0.1 to about 1 wt % of an ether, preferably a cyclic diether having a 5-or 6-membered ring, and most preferably 1,3-dioxolane, and (ii) in therange of about 0.02 to about 0.5 wt % of an epoxyalkane having in therange of 3 to about 7 carbon atoms in the molecule, preferably1,2-epoxybutane. Said weight percentages are based on the total weightof the n-propyl bromide and components (i) and (ii). Preferably, theweight ratio of (i):(ii) is in the range of about 1:1 to about 5:1.

Still another embodiment of this invention is a stabilized solventcomposition comprising a solvent portion which includes at least 90 wt %of n-propyl bromide and a stabilizer system consisting essentially of(i) in the range of about 0.1 to about 1 wt % based on the total weightof the composition, of an ether, preferably a cyclic diether having a 5-or 6-membered ring, and most preferably 1,3-dioxolane, and (ii) in therange of about 0.02 to about 0.5 wt % based on the total weight of thecomposition, of an epoxyalkane having in the range of 3 to about 7carbon atoms in the molecule, preferably 1,2-epoxybutane. Said weightpercentages are based on the total weight of the n-propyl bromide andcomponents (i) and (ii). Preferably the weight ratio of (i):(ii) is inthe range of about 1:1 to about 5:1.

As regards reduced flammability, when the above proportions of theflammable additives (the ether and the epoxyalkane) are blended inton-propyl bromide, and the mixture is combined with a component whichfunctions as a propellant and utilized as an aerosol, the flammabilityof the resulting formulation can be significantly decreased relative toessentially additive-free n-propyl bromide combined with the samecomponent that functions as the propellant. In addition, suchproportions of the flammable additives provide effective stabilizationagainst metal corrosion even though in preferred formulations thecomposition is devoid of a nitroalkane or a nitroaromatic hydrocarbonsuch as nitrobenzene. At the same time the efficacy of the compositionas a solvent is maintained.

Pursuant to an additional embodiment, this invention provides a methodfor cleaning a surface which method comprises applying to the surface acomposition in the form of an aerosol spray, such composition beingcomprised of solvent portion which includes at least 90 wt % of n-propylbromide and a stabilizer system consisting essentially of (i) in therange of about 0.1 to about 1 wt % of an ether, preferably a cyclicdiether having a 5- or 6-membered ring, and most preferably1,3-dioxolane, and (ii) in the range of about 0.02 to about 0.5 wt % ofan epoxyalkane having in the range of 3 to about 7 carbon atoms in themolecule, preferably 1,2-epoxybutane. Said weight percentages are basedon the total weight of the n-propyl bromide and components (i) and (ii).Preferably the weight ratio of (i):(ii) is in the range of about 1:1 toabout 5:1.

The above and other embodiments of this invention will be apparent fromthe ensuing description and the appended claims.

The compositions of this invention contain at least 90 wt %, preferablyat least about 95 wt %, and more preferably at least about 98 wt % ofn-propyl bromide. Most preferably the composition is formed fromn-propyl bromide that has a purity of at least 99 wt %, where such wt %refers to percent of n-propyl bromide plus impurities, if any. n-Propylbromide is available commercially from Albemarle Corporation ofRichmond, Virginia, and from other commercial sources.

In the practice of this invention use is made of ethers that are solublein the solvent portion of the composition. Thus, use can be made ofaliphatic, aromatic and cyclic ethers, which can be either monoethers orpolyethers that are suitably soluble in n-propyl bromide. Suitableethers include, but are not limited to, diethyl ether, dipropyl ether,dibutyl ether, methyl tert-butyl ether, ethyl tert-butyl ether,tert-amyl methyl ether, anisole, tetrahydrofuran, tetrahydropyran, themethyltetrahydrofurans, and similar monoethers. Among suitablepolyethers are such materials as 1,2-methoxyethane, the dimethyl etherof diethylene glycol, the dimethyl ether of triethylene glycol, thedimethyl ether of tetraethylene glycol, 1,4-dioxane, 1,3-dioxolane,2-methyl-1,3-dioxolane, and an analogous polyether solvents.Particularly desirable ethers are cyclic diethers such as 1,4-dioxaneand 1,3- dioxane, and especially 1,3-dioxolane and alkyl substituted1,3-dioxolanes. Particularly preferred as the ether component is1,3-dioxolane. The ether component is used in amounts ranging from about0.1 to about 1.0 wt %, preferably in the range of about 0.2 to about 0.5wt %, and most preferably of the range of about 0.3 to about 0.5 wt %.Said weight percentages are based on the total weight of the n-propylbromide, ether, and epoxyalkane components.

The other additive component required in the compositions of thisinvention is an epoxyalkane having from 3 to about 7 carbon atoms in themolecule. Suitable epoxides include, but are not limited to,1,2-epoxypropane, 1,2-epoxybutane, 2,3-epoxybutane, 1,2-epoxypentane,2,3-epoxypentane, 1,2-epoxyhexane, 2,3-epoxyhexane,4-methyl-1,2-epoxypentane, 1,2-epoxyheptane, 2,3-epoxyheptane,3,4-epoxyheptane, cyclohexene oxide, glycidyl methyl ether, and thelike. Preferred epoxides are the linear 1,2-epoxyalkanes having from 3to about 7 carbon atoms in the molecule, and most preferred is1,2-epoxybutane. The epoxide is used in amounts of about 0.02 wt % toabout 0.5 wt %. Preferably the epoxide is used in an amount in the rangeof about 0.1 to about 0.3 wt %. Said weight percentages are based on thetotal weight of the n-propyl bromide, ether, and epoxyalkane components.

Preferred proportions of the ingredients in the compositions of thisinvention are 98.75 to 99.75 wt % of n-propyl bromide; 0.10 to 1.00 wt %of the ether component; and about 0.15 to about 0.25 wt % of theepoxyalkane component. Most preferred is about 0.15 to about 0.20 wt %of the epoxyalkane, e.g., 1,2-epoxybutane. Most preferably the n-propylbromide has a purity of at least about 99%.

Other additives can be included in the compositions of this inventionprovided they do not materially detract from the flame suppressant orstabilization performance characteristics of the compositions.Preferably the compositions are devoid of any additive ingredient(s)other than one or more ethers and one or more epoxyalkanes (except forthe propellant).

The aerosol containers with which the compositions of this invention areemployed in aerosol spray applications are pressurized aerosol spraycontainers in which a propellant is used. Such devices are known anddescribed in the literature. Any suitable propellant of relatively lowflammability can be used to pressurize the aerosol spray container, suchas, for example, fluorocarbons, fluorohalocarbons, fluorohydrocarbons,and fluorohalohydrocarbons with suitably high vapor pressures includingbromochlorodifluoromethane, 1,1,1-trifluoroethane,1,1,1,2-tetrafluoroethane, dichlorofluoromethane,dichlorodifluoromethane, chlorotrifluoromethane, trichlorofluoromethane,sym-tetrachlorodifluoroethane, 1,2,2-trichloro-1,1,2-trifluoroethane,and sym-dichlorotetrafluoroethane, and mixtures thereof. When using1-fluoro-2,2,2-trifluoroethane as the propellant, the wt % ratio of1-fluoro-2,2,2-trifluoroethane to the sum of the n-propyl bromide, theether, and the epoxyalkane in the cleaning composition is preferably atleast about 30/70. Said wt % ratio is most preferably in the range ofabout 30/70 to about 40/60.

The solvent compositions of the invention have particular utility innon-spark-free applications and environments as aerosol spray cleaningcompositions. Preferably, the surface to be cleaned in the presence ofpotential ignition sources such as electrical switches or the likeshould be at a relatively low temperature such as from about 25° C. toabout 60° C. The aerosol spray discharge is applied to the surface. Thedischarge functions as a cleaner, and is either removed, as by wipingwith a cloth, or is allowed to drip off.

The following demonstrates the exceptional non-flammability andnon-corrosiveness of the solvent compositions of this invention. Theexamples are not intended to constitute limitations on the invention,but rather are presented for purposes of illustration.

EXAMPLE I

A solvent composition was prepared by mixing the following ingredientstogether:

99.4 wt % of n-propyl bromide

0.4 wt % of 1,3-dioxolane

0.2 wt % of 1,2-epoxybutane

The solvent composition was combined with propellant HFC-134a(1-fluoro-2,2,2-trifluoroethane) in the weight ratios listed in theTable. The solvent-propellant combination was confined to twelve-ouncecans in ten-ounce portions. The sample was then subjected to a FlameExtension Test set forth in Consumer Products Safety Commissionregulations on hazardous substance (16 CFR 1500.45-46), which is alsoASTM test procedure D 3065. In the test, a methanol burner with a 2350wipe in the lid to act as a wick was used a source of ignition. Thedischarge from the aerosol can was sprayed through the top third of theburner flame from a distance of 6 inches continually until the can wasempty. The results of the tests are summarized in the Table.

TABLE N-propyl bromide:1-fluoro-2,2,2- Flame Substance testedtrifluoroethane (wt %:wt %) extension Pure n-propyl bromide* 70:30 10inches (NPB) NPB with stabilizers of 70:30  6 inches Example 1 Puren-propyl bromide* 68:32 10 inches (NPB) NPB with stabilizers of 68:32  3inches Example 1 *contains 0.15 wt % 1,2-epoxybutane

EXAMPLE II

A solvent composition was prepared containing 0.4 wt % of 1,3-dioxolane,0.15 wt % of 1,2-epoxybutane, and 99.45 wt % of n-propyl bromide. Apiece of tin-plated carbon steel of the grade used for industrialaerosol containers was subjected to Military Specifications Test no.MIL-T-81533A 4.4.9. In this test 0.5-inch by 5-inch panels ofaerosol-can grade metal are polished with a No. 1 cloth until the panelsare free from tarnish or oxide residue. Panels are then washed withdetergent and water, rinsed with distilled water, then acetone, andallowed to dry. The panels are placed in a 500 ml Erlenmeyer flask witha ground glass neck, and covered to a depth of 1 inch with the aboven-propyl bromide formulation. The resultant test sample is refluxed for24 hours over a light shielded 150 watt light bulb. The panel isremoved, rinsed with refluxate, and examined for corrosion. It was foundthat the test panel that had been refluxed with the above n-propylbromide formulation exhibited no observable corrosion.

It is to be understood that the reactants and components referred to bychemical name or by formula anywhere in the specification or claimshereof, whether referred to in the singular or plural, are identified asthey exist prior to coming into contact with another substance referredto by chemical name or chemical type (e.g., another reactant, a solvent,or etc.). It matters not what preliminary chemical changes,transformations and/or reactions, if any, take place in the resultingmixture or solution or reaction medium as such changes, transformationsand/or reactions are the natural result of bringing the specifiedreactants and/or components together under the conditions called forpursuant to this disclosure. Thus the reactants and components areidentified as ingredients to be brought together in connection withperforming a desired chemical reaction or in forming a mixture to beused in conducting a desired reaction. Accordingly, even though theclaims hereinafter may refer to substances, components and/oringredients in the present tense (“comprises,” “is,” etc.), thereference is to the substance, component or ingredient just as itexisted at the time just before it was first contacted, blended or mixedwith one or more other substances, components and/or ingredients inaccordance with the present disclosure. Thus, the fact that a substance,component or ingredient may have lost its original identity through achemical reaction or transformation through the course of contacting,blending or mixing operations, if conducted in accordance with thisdisclosure and with the application of common sense and the ordinaryskill of a chemist, is thus wholly immaterial for an accurateunderstanding and appreciation of the true meaning and substance of thisdisclosure and the claims thereof.

Each and every patent or publication referred to in any portion of thisspecification is incorporated in toto into this disclosure by reference,as if fully set forth herein.

This invention is susceptible to considerable variation in its practice.Therefore, the foregoing description is not intended to limit, andshould not be construed as limiting, the invention to the particularexemplifications presented hereinabove. Rather, what is intended to becovered is as set forth in the ensuing claims and the equivalentsthereof permitted as a matter of law.

What is claimed is:
 1. A spray dispenser containing a composition devoidof nitroalkane and devoid of nitroaromatic hydrocarbon, said compositioncomprising (i) a solvent portion in which the solvent consists ofn-propyl bromide of a purity of at least 99 wt % having dissolvedtherein a stabilizer system consisting essentially of (a) 1,3-dioxolaneand (b) one or more epoxyalkanes having in the range of 3 to about 7carbon atoms in the molecule, in proportions such that said compositionis rendered more flame resistant when in the form of a spray dispersedin air under the conditions of ASTM test procedure D 3065 and when using1,1,1,2-tetrafluoroethane as the propellant for said composition in saidtest procedure.
 2. A spray dispenser of claim 1 wherein (a) is presentin an amount in the range of about 0.1 to about 1 wt %, and (b) ispresent in an amount in the range of about 0.02 to about 0.5 wt %, bothsuch percentages being based on the total weight of said n-propylbromide plus the weights of (a) and (b).
 3. A spray dispenser of claim 1wherein (b) is 1,2-epoxybutane.
 4. A spray dispenser of claim 1 whereinthe weight ratio of (a):(b) is in the range of about 1:1 to about 5:1.5. A spray dispenser of claim 1 wherein the concentration of (a) is inthe range of about 0.2 to about 0.5 wt %, and the concentration of (b)is in the range of about 0.15 to about 0.25 wt %, said percentages beingbased on the total weight of the n-propyl bromide and of components (a)and (b).
 6. A spray dispenser of claim 1 wherein said compositionconsists essentially of about 99.40 wt % of n-propyl bromide, about 0.40wt % of 1,3-dioxolane, and about 0.20 wt % of 1,2-epoxybutane.
 7. Aspray dispenser of claim 1 wherein said composition consists essentiallyof about 99.45 wt % of n-propyl bromide, about 0.40 wt % of1,3-dioxolane, and about 0.15 wt % of 1,2-epoxybutane.
 8. A spraydispenser as in any of claims 1 or 3, 7 wherein the dispenser is apressurized dispenser containing a propellant of low flammability.
 9. Aspray dispenser of claim 1 or 2 wherein said dispenser is a pressurizeddispenser containing a propellant consisting of1,1,1,2-tetrafluoroethane.
 10. A spray dispenser of claim 1 wherein saiddispenser is a pressurized dispenser containing as the propellant one ora mixture of propellants selected from fluorocarbons, fluorohalocarbons,fluorohydrocarbons, and fluorohalohydrocarbons.
 11. A spray dispenser ofclaim 1 or 2 wherein said dispenser is a pressurized dispensercontaining as the propellant, a propellant selected from the groupconsisting of bromochlorodifluoromethane, 1,1,1-trifluoroethane,dichlorofluoromethane, dichlorodifluoromethane, chlorotrifluoromethane,trichlorofluoromethane, symtetrachlorodifluoroethane,1,2,2-trichloro-1,1,2-trifluoroethane, and symdichlorotetrafluoroethane,and mixtures thereof.
 12. A method of cleaning a surface, which methodcomprises applying to said surface as an aerosol spray, a compositiondevoid of nitroalkane and devoid of nitroaromatic hydrocarbon, saidcomposition comprising (i) a solvent portion in which the solventconsists of n-propyl bromide of a purity of at least 99 wt % havingdissolved therein (ii) a stabilizer system consisting essentially of (a)1, 3 dioxolane and (b) one or more epoxyalkanes having in the range of 3to about 7 carbon atoms in the molecule, in proportions such that saidcomposition is rendered more flame resistant when in the form of a spraydispersed in air under the conditions of ASTM test procedure D 3065 andwhen using 1,1,1,2-tetrafluoroethane as the propellant for saidcomposition in said test procedure.
 13. A method of claim 12 whereinsaid composition is applied as the aerosol spray discharge from anaerosol dispenser in which 1,1,1,2-tetrafluoroethane is the propellant,and wherein the wt % ratio of 1,1,1,2-tetrafluoroethane to the sum ofthe n-propyl bromide, the ether, and the epoxyalkane is about 30/70 orhigher.
 14. A method of claim 2 wherein said composition is applied asthe aerosol spray discharge from an aerosol dispenser in which one or amixture of propellants of low flammability selected from fluorocarbons,fluorohalocarbons, fluorohydrocarbons, and fluorohalohydrocarbons is thepropellant.
 15. A method of claim 14 wherein said propellant is selectedfrom bromochlorodifluoromethane, 1,1,1-trifluoroethane,dichlorofluoromethane, dichlorodifluoromethane, chlorotrifluoromethane,trichlorofluoromethane, sym-tetrachlorodifluoroethane, 1,2,2-trichloro-1,1,2-trifluoroethane, and sym-dichlorotetrafluoroethane, and mixturesthereof.
 16. A method of claim 12 wherein said composition is devoid ofany additive component other than (a), (b), and if used, a propellant.17. A method of claim 12 wherein the amount of (a) in said compositionis in the range of about 0.2 to about 0.5 wt %, and the amount of (b) isin the range of about 0.15 to about 0.25 wt %, said percentages beingbased on the total weight of the n-propyl bromide and of components (a)and (b).
 18. A method of claim 12 wherein said composition consistsessentially of about 99.40 wt % of said n-propyl bromide, about 0.40 wt% of 1,3-dioxolane, and about 0.20 wt % of 1,2-epoxybutane.
 19. A methodof claim 12 wherein said composition consists essentially of about 99.45wt % of said n-propyl bromide, about 0.40 wt % of 1,3-dioxolane, andabout 0.15 wt % of 1,2-epoxybutane.
 20. A composition devoid ofnitroalkanes and devoid of nitroaromatic hydrocarbons, said compositionconsisting essentially of about 98.75 to about 99.75 wt % of n-propylbromide, about 0.10 to about 1.00 wt % of 1,3-dioxolane, and about 0.15to about 0.25 wt % of 1,2-epoxybutane, the total of said weightpercentages being 100 wt %.
 21. A composition of claim 20 wherein saidcomposition consists essentially of about 99.40 to about 99.45 wt % ofn-propyl bromide, about 0.40 wt % of 1,3-dioxolane, and about 0.15 toabout 0.20 wt % of 1,2-epoxybutane, the total of said weight percentagesbeing 100 wt %.
 22. A composition of claim 21 wherein said compositionconsists essentially of about 99.40% of n-propyl bromide, about 0.40 wt% of 1,3-dioxolane, and about 0.20 wt % of 1,2-epoxybutane.
 23. Acomposition of claim 21 wherein said composition consists essentially ofabout 99.45% of n-propyl bromide, about 0.40 wt % of 1,3-dioxolane, andabout 0.15 wt % of 1,2-epoxybutane.